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<pre><span class="sourceLineNo">001</span>/*<a name="line.1"></a>
<span class="sourceLineNo">002</span> * Copyright (C) 2007 The Guava Authors<a name="line.2"></a>
<span class="sourceLineNo">003</span> *<a name="line.3"></a>
<span class="sourceLineNo">004</span> * Licensed under the Apache License, Version 2.0 (the "License");<a name="line.4"></a>
<span class="sourceLineNo">005</span> * you may not use this file except in compliance with the License.<a name="line.5"></a>
<span class="sourceLineNo">006</span> * You may obtain a copy of the License at<a name="line.6"></a>
<span class="sourceLineNo">007</span> *<a name="line.7"></a>
<span class="sourceLineNo">008</span> * http://www.apache.org/licenses/LICENSE-2.0<a name="line.8"></a>
<span class="sourceLineNo">009</span> *<a name="line.9"></a>
<span class="sourceLineNo">010</span> * Unless required by applicable law or agreed to in writing, software<a name="line.10"></a>
<span class="sourceLineNo">011</span> * distributed under the License is distributed on an "AS IS" BASIS,<a name="line.11"></a>
<span class="sourceLineNo">012</span> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.<a name="line.12"></a>
<span class="sourceLineNo">013</span> * See the License for the specific language governing permissions and<a name="line.13"></a>
<span class="sourceLineNo">014</span> * limitations under the License.<a name="line.14"></a>
<span class="sourceLineNo">015</span> */<a name="line.15"></a>
<span class="sourceLineNo">016</span><a name="line.16"></a>
<span class="sourceLineNo">017</span>package com.google.common.base;<a name="line.17"></a>
<span class="sourceLineNo">018</span><a name="line.18"></a>
<span class="sourceLineNo">019</span>import com.google.common.annotations.GwtCompatible;<a name="line.19"></a>
<span class="sourceLineNo">020</span>import com.google.common.annotations.VisibleForTesting;<a name="line.20"></a>
<span class="sourceLineNo">021</span><a name="line.21"></a>
<span class="sourceLineNo">022</span>import java.util.NoSuchElementException;<a name="line.22"></a>
<span class="sourceLineNo">023</span><a name="line.23"></a>
<span class="sourceLineNo">024</span>import javax.annotation.Nullable;<a name="line.24"></a>
<span class="sourceLineNo">025</span><a name="line.25"></a>
<span class="sourceLineNo">026</span>/**<a name="line.26"></a>
<span class="sourceLineNo">027</span> * Simple static methods to be called at the start of your own methods to verify<a name="line.27"></a>
<span class="sourceLineNo">028</span> * correct arguments and state. This allows constructs such as<a name="line.28"></a>
<span class="sourceLineNo">029</span> * &lt;pre&gt;<a name="line.29"></a>
<span class="sourceLineNo">030</span> *     if (count &lt;= 0) {<a name="line.30"></a>
<span class="sourceLineNo">031</span> *       throw new IllegalArgumentException("must be positive: " + count);<a name="line.31"></a>
<span class="sourceLineNo">032</span> *     }&lt;/pre&gt;<a name="line.32"></a>
<span class="sourceLineNo">033</span> *<a name="line.33"></a>
<span class="sourceLineNo">034</span> * to be replaced with the more compact<a name="line.34"></a>
<span class="sourceLineNo">035</span> * &lt;pre&gt;<a name="line.35"></a>
<span class="sourceLineNo">036</span> *     checkArgument(count &gt; 0, "must be positive: %s", count);&lt;/pre&gt;<a name="line.36"></a>
<span class="sourceLineNo">037</span> *<a name="line.37"></a>
<span class="sourceLineNo">038</span> * Note that the sense of the expression is inverted; with {@code Preconditions}<a name="line.38"></a>
<span class="sourceLineNo">039</span> * you declare what you expect to be &lt;i&gt;true&lt;/i&gt;, just as you do with an<a name="line.39"></a>
<span class="sourceLineNo">040</span> * &lt;a href="http://java.sun.com/j2se/1.5.0/docs/guide/language/assert.html"&gt;<a name="line.40"></a>
<span class="sourceLineNo">041</span> * {@code assert}&lt;/a&gt; or a JUnit {@code assertTrue} call.<a name="line.41"></a>
<span class="sourceLineNo">042</span> *<a name="line.42"></a>
<span class="sourceLineNo">043</span> * &lt;p&gt;&lt;b&gt;Warning:&lt;/b&gt; only the {@code "%s"} specifier is recognized as a<a name="line.43"></a>
<span class="sourceLineNo">044</span> * placeholder in these messages, not the full range of {@link<a name="line.44"></a>
<span class="sourceLineNo">045</span> * String#format(String, Object[])} specifiers.<a name="line.45"></a>
<span class="sourceLineNo">046</span> *<a name="line.46"></a>
<span class="sourceLineNo">047</span> * &lt;p&gt;Take care not to confuse precondition checking with other similar types<a name="line.47"></a>
<span class="sourceLineNo">048</span> * of checks! Precondition exceptions -- including those provided here, but also<a name="line.48"></a>
<span class="sourceLineNo">049</span> * {@link IndexOutOfBoundsException}, {@link NoSuchElementException}, {@link<a name="line.49"></a>
<span class="sourceLineNo">050</span> * UnsupportedOperationException} and others -- are used to signal that the<a name="line.50"></a>
<span class="sourceLineNo">051</span> * &lt;i&gt;calling method&lt;/i&gt; has made an error. This tells the caller that it should<a name="line.51"></a>
<span class="sourceLineNo">052</span> * not have invoked the method when it did, with the arguments it did, or<a name="line.52"></a>
<span class="sourceLineNo">053</span> * perhaps ever. Postcondition or other invariant failures should not throw<a name="line.53"></a>
<span class="sourceLineNo">054</span> * these types of exceptions.<a name="line.54"></a>
<span class="sourceLineNo">055</span> *<a name="line.55"></a>
<span class="sourceLineNo">056</span> * &lt;p&gt;See the Guava User Guide on &lt;a href=<a name="line.56"></a>
<span class="sourceLineNo">057</span> * "http://code.google.com/p/guava-libraries/wiki/PreconditionsExplained"&gt;<a name="line.57"></a>
<span class="sourceLineNo">058</span> * using {@code Preconditions}&lt;/a&gt;.<a name="line.58"></a>
<span class="sourceLineNo">059</span> *<a name="line.59"></a>
<span class="sourceLineNo">060</span> * @author Kevin Bourrillion<a name="line.60"></a>
<span class="sourceLineNo">061</span> * @since 2.0 (imported from Google Collections Library)<a name="line.61"></a>
<span class="sourceLineNo">062</span> */<a name="line.62"></a>
<span class="sourceLineNo">063</span>@GwtCompatible<a name="line.63"></a>
<span class="sourceLineNo">064</span>public final class Preconditions {<a name="line.64"></a>
<span class="sourceLineNo">065</span>  private Preconditions() {}<a name="line.65"></a>
<span class="sourceLineNo">066</span><a name="line.66"></a>
<span class="sourceLineNo">067</span>  /**<a name="line.67"></a>
<span class="sourceLineNo">068</span>   * Ensures the truth of an expression involving one or more parameters to the<a name="line.68"></a>
<span class="sourceLineNo">069</span>   * calling method.<a name="line.69"></a>
<span class="sourceLineNo">070</span>   *<a name="line.70"></a>
<span class="sourceLineNo">071</span>   * @param expression a boolean expression<a name="line.71"></a>
<span class="sourceLineNo">072</span>   * @throws IllegalArgumentException if {@code expression} is false<a name="line.72"></a>
<span class="sourceLineNo">073</span>   */<a name="line.73"></a>
<span class="sourceLineNo">074</span>  public static void checkArgument(boolean expression) {<a name="line.74"></a>
<span class="sourceLineNo">075</span>    if (!expression) {<a name="line.75"></a>
<span class="sourceLineNo">076</span>      throw new IllegalArgumentException();<a name="line.76"></a>
<span class="sourceLineNo">077</span>    }<a name="line.77"></a>
<span class="sourceLineNo">078</span>  }<a name="line.78"></a>
<span class="sourceLineNo">079</span><a name="line.79"></a>
<span class="sourceLineNo">080</span>  /**<a name="line.80"></a>
<span class="sourceLineNo">081</span>   * Ensures the truth of an expression involving one or more parameters to the<a name="line.81"></a>
<span class="sourceLineNo">082</span>   * calling method.<a name="line.82"></a>
<span class="sourceLineNo">083</span>   *<a name="line.83"></a>
<span class="sourceLineNo">084</span>   * @param expression a boolean expression<a name="line.84"></a>
<span class="sourceLineNo">085</span>   * @param errorMessage the exception message to use if the check fails; will<a name="line.85"></a>
<span class="sourceLineNo">086</span>   *     be converted to a string using {@link String#valueOf(Object)}<a name="line.86"></a>
<span class="sourceLineNo">087</span>   * @throws IllegalArgumentException if {@code expression} is false<a name="line.87"></a>
<span class="sourceLineNo">088</span>   */<a name="line.88"></a>
<span class="sourceLineNo">089</span>  public static void checkArgument(<a name="line.89"></a>
<span class="sourceLineNo">090</span>      boolean expression, @Nullable Object errorMessage) {<a name="line.90"></a>
<span class="sourceLineNo">091</span>    if (!expression) {<a name="line.91"></a>
<span class="sourceLineNo">092</span>      throw new IllegalArgumentException(String.valueOf(errorMessage));<a name="line.92"></a>
<span class="sourceLineNo">093</span>    }<a name="line.93"></a>
<span class="sourceLineNo">094</span>  }<a name="line.94"></a>
<span class="sourceLineNo">095</span><a name="line.95"></a>
<span class="sourceLineNo">096</span>  /**<a name="line.96"></a>
<span class="sourceLineNo">097</span>   * Ensures the truth of an expression involving one or more parameters to the<a name="line.97"></a>
<span class="sourceLineNo">098</span>   * calling method.<a name="line.98"></a>
<span class="sourceLineNo">099</span>   *<a name="line.99"></a>
<span class="sourceLineNo">100</span>   * @param expression a boolean expression<a name="line.100"></a>
<span class="sourceLineNo">101</span>   * @param errorMessageTemplate a template for the exception message should the<a name="line.101"></a>
<span class="sourceLineNo">102</span>   *     check fail. The message is formed by replacing each {@code %s}<a name="line.102"></a>
<span class="sourceLineNo">103</span>   *     placeholder in the template with an argument. These are matched by<a name="line.103"></a>
<span class="sourceLineNo">104</span>   *     position - the first {@code %s} gets {@code errorMessageArgs[0]}, etc.<a name="line.104"></a>
<span class="sourceLineNo">105</span>   *     Unmatched arguments will be appended to the formatted message in square<a name="line.105"></a>
<span class="sourceLineNo">106</span>   *     braces. Unmatched placeholders will be left as-is.<a name="line.106"></a>
<span class="sourceLineNo">107</span>   * @param errorMessageArgs the arguments to be substituted into the message<a name="line.107"></a>
<span class="sourceLineNo">108</span>   *     template. Arguments are converted to strings using<a name="line.108"></a>
<span class="sourceLineNo">109</span>   *     {@link String#valueOf(Object)}.<a name="line.109"></a>
<span class="sourceLineNo">110</span>   * @throws IllegalArgumentException if {@code expression} is false<a name="line.110"></a>
<span class="sourceLineNo">111</span>   * @throws NullPointerException if the check fails and either {@code<a name="line.111"></a>
<span class="sourceLineNo">112</span>   *     errorMessageTemplate} or {@code errorMessageArgs} is null (don't let<a name="line.112"></a>
<span class="sourceLineNo">113</span>   *     this happen)<a name="line.113"></a>
<span class="sourceLineNo">114</span>   */<a name="line.114"></a>
<span class="sourceLineNo">115</span>  public static void checkArgument(boolean expression,<a name="line.115"></a>
<span class="sourceLineNo">116</span>      @Nullable String errorMessageTemplate,<a name="line.116"></a>
<span class="sourceLineNo">117</span>      @Nullable Object... errorMessageArgs) {<a name="line.117"></a>
<span class="sourceLineNo">118</span>    if (!expression) {<a name="line.118"></a>
<span class="sourceLineNo">119</span>      throw new IllegalArgumentException(<a name="line.119"></a>
<span class="sourceLineNo">120</span>          format(errorMessageTemplate, errorMessageArgs));<a name="line.120"></a>
<span class="sourceLineNo">121</span>    }<a name="line.121"></a>
<span class="sourceLineNo">122</span>  }<a name="line.122"></a>
<span class="sourceLineNo">123</span><a name="line.123"></a>
<span class="sourceLineNo">124</span>  /**<a name="line.124"></a>
<span class="sourceLineNo">125</span>   * Ensures the truth of an expression involving the state of the calling<a name="line.125"></a>
<span class="sourceLineNo">126</span>   * instance, but not involving any parameters to the calling method.<a name="line.126"></a>
<span class="sourceLineNo">127</span>   *<a name="line.127"></a>
<span class="sourceLineNo">128</span>   * @param expression a boolean expression<a name="line.128"></a>
<span class="sourceLineNo">129</span>   * @throws IllegalStateException if {@code expression} is false<a name="line.129"></a>
<span class="sourceLineNo">130</span>   */<a name="line.130"></a>
<span class="sourceLineNo">131</span>  public static void checkState(boolean expression) {<a name="line.131"></a>
<span class="sourceLineNo">132</span>    if (!expression) {<a name="line.132"></a>
<span class="sourceLineNo">133</span>      throw new IllegalStateException();<a name="line.133"></a>
<span class="sourceLineNo">134</span>    }<a name="line.134"></a>
<span class="sourceLineNo">135</span>  }<a name="line.135"></a>
<span class="sourceLineNo">136</span><a name="line.136"></a>
<span class="sourceLineNo">137</span>  /**<a name="line.137"></a>
<span class="sourceLineNo">138</span>   * Ensures the truth of an expression involving the state of the calling<a name="line.138"></a>
<span class="sourceLineNo">139</span>   * instance, but not involving any parameters to the calling method.<a name="line.139"></a>
<span class="sourceLineNo">140</span>   *<a name="line.140"></a>
<span class="sourceLineNo">141</span>   * @param expression a boolean expression<a name="line.141"></a>
<span class="sourceLineNo">142</span>   * @param errorMessage the exception message to use if the check fails; will<a name="line.142"></a>
<span class="sourceLineNo">143</span>   *     be converted to a string using {@link String#valueOf(Object)}<a name="line.143"></a>
<span class="sourceLineNo">144</span>   * @throws IllegalStateException if {@code expression} is false<a name="line.144"></a>
<span class="sourceLineNo">145</span>   */<a name="line.145"></a>
<span class="sourceLineNo">146</span>  public static void checkState(<a name="line.146"></a>
<span class="sourceLineNo">147</span>      boolean expression, @Nullable Object errorMessage) {<a name="line.147"></a>
<span class="sourceLineNo">148</span>    if (!expression) {<a name="line.148"></a>
<span class="sourceLineNo">149</span>      throw new IllegalStateException(String.valueOf(errorMessage));<a name="line.149"></a>
<span class="sourceLineNo">150</span>    }<a name="line.150"></a>
<span class="sourceLineNo">151</span>  }<a name="line.151"></a>
<span class="sourceLineNo">152</span><a name="line.152"></a>
<span class="sourceLineNo">153</span>  /**<a name="line.153"></a>
<span class="sourceLineNo">154</span>   * Ensures the truth of an expression involving the state of the calling<a name="line.154"></a>
<span class="sourceLineNo">155</span>   * instance, but not involving any parameters to the calling method.<a name="line.155"></a>
<span class="sourceLineNo">156</span>   *<a name="line.156"></a>
<span class="sourceLineNo">157</span>   * @param expression a boolean expression<a name="line.157"></a>
<span class="sourceLineNo">158</span>   * @param errorMessageTemplate a template for the exception message should the<a name="line.158"></a>
<span class="sourceLineNo">159</span>   *     check fail. The message is formed by replacing each {@code %s}<a name="line.159"></a>
<span class="sourceLineNo">160</span>   *     placeholder in the template with an argument. These are matched by<a name="line.160"></a>
<span class="sourceLineNo">161</span>   *     position - the first {@code %s} gets {@code errorMessageArgs[0]}, etc.<a name="line.161"></a>
<span class="sourceLineNo">162</span>   *     Unmatched arguments will be appended to the formatted message in square<a name="line.162"></a>
<span class="sourceLineNo">163</span>   *     braces. Unmatched placeholders will be left as-is.<a name="line.163"></a>
<span class="sourceLineNo">164</span>   * @param errorMessageArgs the arguments to be substituted into the message<a name="line.164"></a>
<span class="sourceLineNo">165</span>   *     template. Arguments are converted to strings using<a name="line.165"></a>
<span class="sourceLineNo">166</span>   *     {@link String#valueOf(Object)}.<a name="line.166"></a>
<span class="sourceLineNo">167</span>   * @throws IllegalStateException if {@code expression} is false<a name="line.167"></a>
<span class="sourceLineNo">168</span>   * @throws NullPointerException if the check fails and either {@code<a name="line.168"></a>
<span class="sourceLineNo">169</span>   *     errorMessageTemplate} or {@code errorMessageArgs} is null (don't let<a name="line.169"></a>
<span class="sourceLineNo">170</span>   *     this happen)<a name="line.170"></a>
<span class="sourceLineNo">171</span>   */<a name="line.171"></a>
<span class="sourceLineNo">172</span>  public static void checkState(boolean expression,<a name="line.172"></a>
<span class="sourceLineNo">173</span>      @Nullable String errorMessageTemplate,<a name="line.173"></a>
<span class="sourceLineNo">174</span>      @Nullable Object... errorMessageArgs) {<a name="line.174"></a>
<span class="sourceLineNo">175</span>    if (!expression) {<a name="line.175"></a>
<span class="sourceLineNo">176</span>      throw new IllegalStateException(<a name="line.176"></a>
<span class="sourceLineNo">177</span>          format(errorMessageTemplate, errorMessageArgs));<a name="line.177"></a>
<span class="sourceLineNo">178</span>    }<a name="line.178"></a>
<span class="sourceLineNo">179</span>  }<a name="line.179"></a>
<span class="sourceLineNo">180</span><a name="line.180"></a>
<span class="sourceLineNo">181</span>  /**<a name="line.181"></a>
<span class="sourceLineNo">182</span>   * Ensures that an object reference passed as a parameter to the calling<a name="line.182"></a>
<span class="sourceLineNo">183</span>   * method is not null.<a name="line.183"></a>
<span class="sourceLineNo">184</span>   *<a name="line.184"></a>
<span class="sourceLineNo">185</span>   * @param reference an object reference<a name="line.185"></a>
<span class="sourceLineNo">186</span>   * @return the non-null reference that was validated<a name="line.186"></a>
<span class="sourceLineNo">187</span>   * @throws NullPointerException if {@code reference} is null<a name="line.187"></a>
<span class="sourceLineNo">188</span>   */<a name="line.188"></a>
<span class="sourceLineNo">189</span>  public static &lt;T&gt; T checkNotNull(T reference) {<a name="line.189"></a>
<span class="sourceLineNo">190</span>    if (reference == null) {<a name="line.190"></a>
<span class="sourceLineNo">191</span>      throw new NullPointerException();<a name="line.191"></a>
<span class="sourceLineNo">192</span>    }<a name="line.192"></a>
<span class="sourceLineNo">193</span>    return reference;<a name="line.193"></a>
<span class="sourceLineNo">194</span>  }<a name="line.194"></a>
<span class="sourceLineNo">195</span><a name="line.195"></a>
<span class="sourceLineNo">196</span>  /**<a name="line.196"></a>
<span class="sourceLineNo">197</span>   * Ensures that an object reference passed as a parameter to the calling<a name="line.197"></a>
<span class="sourceLineNo">198</span>   * method is not null.<a name="line.198"></a>
<span class="sourceLineNo">199</span>   *<a name="line.199"></a>
<span class="sourceLineNo">200</span>   * @param reference an object reference<a name="line.200"></a>
<span class="sourceLineNo">201</span>   * @param errorMessage the exception message to use if the check fails; will<a name="line.201"></a>
<span class="sourceLineNo">202</span>   *     be converted to a string using {@link String#valueOf(Object)}<a name="line.202"></a>
<span class="sourceLineNo">203</span>   * @return the non-null reference that was validated<a name="line.203"></a>
<span class="sourceLineNo">204</span>   * @throws NullPointerException if {@code reference} is null<a name="line.204"></a>
<span class="sourceLineNo">205</span>   */<a name="line.205"></a>
<span class="sourceLineNo">206</span>  public static &lt;T&gt; T checkNotNull(T reference, @Nullable Object errorMessage) {<a name="line.206"></a>
<span class="sourceLineNo">207</span>    if (reference == null) {<a name="line.207"></a>
<span class="sourceLineNo">208</span>      throw new NullPointerException(String.valueOf(errorMessage));<a name="line.208"></a>
<span class="sourceLineNo">209</span>    }<a name="line.209"></a>
<span class="sourceLineNo">210</span>    return reference;<a name="line.210"></a>
<span class="sourceLineNo">211</span>  }<a name="line.211"></a>
<span class="sourceLineNo">212</span><a name="line.212"></a>
<span class="sourceLineNo">213</span>  /**<a name="line.213"></a>
<span class="sourceLineNo">214</span>   * Ensures that an object reference passed as a parameter to the calling<a name="line.214"></a>
<span class="sourceLineNo">215</span>   * method is not null.<a name="line.215"></a>
<span class="sourceLineNo">216</span>   *<a name="line.216"></a>
<span class="sourceLineNo">217</span>   * @param reference an object reference<a name="line.217"></a>
<span class="sourceLineNo">218</span>   * @param errorMessageTemplate a template for the exception message should the<a name="line.218"></a>
<span class="sourceLineNo">219</span>   *     check fail. The message is formed by replacing each {@code %s}<a name="line.219"></a>
<span class="sourceLineNo">220</span>   *     placeholder in the template with an argument. These are matched by<a name="line.220"></a>
<span class="sourceLineNo">221</span>   *     position - the first {@code %s} gets {@code errorMessageArgs[0]}, etc.<a name="line.221"></a>
<span class="sourceLineNo">222</span>   *     Unmatched arguments will be appended to the formatted message in square<a name="line.222"></a>
<span class="sourceLineNo">223</span>   *     braces. Unmatched placeholders will be left as-is.<a name="line.223"></a>
<span class="sourceLineNo">224</span>   * @param errorMessageArgs the arguments to be substituted into the message<a name="line.224"></a>
<span class="sourceLineNo">225</span>   *     template. Arguments are converted to strings using<a name="line.225"></a>
<span class="sourceLineNo">226</span>   *     {@link String#valueOf(Object)}.<a name="line.226"></a>
<span class="sourceLineNo">227</span>   * @return the non-null reference that was validated<a name="line.227"></a>
<span class="sourceLineNo">228</span>   * @throws NullPointerException if {@code reference} is null<a name="line.228"></a>
<span class="sourceLineNo">229</span>   */<a name="line.229"></a>
<span class="sourceLineNo">230</span>  public static &lt;T&gt; T checkNotNull(T reference,<a name="line.230"></a>
<span class="sourceLineNo">231</span>      @Nullable String errorMessageTemplate,<a name="line.231"></a>
<span class="sourceLineNo">232</span>      @Nullable Object... errorMessageArgs) {<a name="line.232"></a>
<span class="sourceLineNo">233</span>    if (reference == null) {<a name="line.233"></a>
<span class="sourceLineNo">234</span>      // If either of these parameters is null, the right thing happens anyway<a name="line.234"></a>
<span class="sourceLineNo">235</span>      throw new NullPointerException(<a name="line.235"></a>
<span class="sourceLineNo">236</span>          format(errorMessageTemplate, errorMessageArgs));<a name="line.236"></a>
<span class="sourceLineNo">237</span>    }<a name="line.237"></a>
<span class="sourceLineNo">238</span>    return reference;<a name="line.238"></a>
<span class="sourceLineNo">239</span>  }<a name="line.239"></a>
<span class="sourceLineNo">240</span><a name="line.240"></a>
<span class="sourceLineNo">241</span>  /*<a name="line.241"></a>
<span class="sourceLineNo">242</span>   * All recent hotspots (as of 2009) *really* like to have the natural code<a name="line.242"></a>
<span class="sourceLineNo">243</span>   *<a name="line.243"></a>
<span class="sourceLineNo">244</span>   * if (guardExpression) {<a name="line.244"></a>
<span class="sourceLineNo">245</span>   *    throw new BadException(messageExpression);<a name="line.245"></a>
<span class="sourceLineNo">246</span>   * }<a name="line.246"></a>
<span class="sourceLineNo">247</span>   *<a name="line.247"></a>
<span class="sourceLineNo">248</span>   * refactored so that messageExpression is moved to a separate<a name="line.248"></a>
<span class="sourceLineNo">249</span>   * String-returning method.<a name="line.249"></a>
<span class="sourceLineNo">250</span>   *<a name="line.250"></a>
<span class="sourceLineNo">251</span>   * if (guardExpression) {<a name="line.251"></a>
<span class="sourceLineNo">252</span>   *    throw new BadException(badMsg(...));<a name="line.252"></a>
<span class="sourceLineNo">253</span>   * }<a name="line.253"></a>
<span class="sourceLineNo">254</span>   *<a name="line.254"></a>
<span class="sourceLineNo">255</span>   * The alternative natural refactorings into void or Exception-returning<a name="line.255"></a>
<span class="sourceLineNo">256</span>   * methods are much slower.  This is a big deal - we're talking factors of<a name="line.256"></a>
<span class="sourceLineNo">257</span>   * 2-8 in microbenchmarks, not just 10-20%.  (This is a hotspot optimizer<a name="line.257"></a>
<span class="sourceLineNo">258</span>   * bug, which should be fixed, but that's a separate, big project).<a name="line.258"></a>
<span class="sourceLineNo">259</span>   *<a name="line.259"></a>
<span class="sourceLineNo">260</span>   * The coding pattern above is heavily used in java.util, e.g. in ArrayList.<a name="line.260"></a>
<span class="sourceLineNo">261</span>   * There is a RangeCheckMicroBenchmark in the JDK that was used to test this.<a name="line.261"></a>
<span class="sourceLineNo">262</span>   *<a name="line.262"></a>
<span class="sourceLineNo">263</span>   * But the methods in this class want to throw different exceptions,<a name="line.263"></a>
<span class="sourceLineNo">264</span>   * depending on the args, so it appears that this pattern is not directly<a name="line.264"></a>
<span class="sourceLineNo">265</span>   * applicable.  But we can use the ridiculous, devious trick of throwing an<a name="line.265"></a>
<span class="sourceLineNo">266</span>   * exception in the middle of the construction of another exception.<a name="line.266"></a>
<span class="sourceLineNo">267</span>   * Hotspot is fine with that.<a name="line.267"></a>
<span class="sourceLineNo">268</span>   */<a name="line.268"></a>
<span class="sourceLineNo">269</span><a name="line.269"></a>
<span class="sourceLineNo">270</span>  /**<a name="line.270"></a>
<span class="sourceLineNo">271</span>   * Ensures that {@code index} specifies a valid &lt;i&gt;element&lt;/i&gt; in an array,<a name="line.271"></a>
<span class="sourceLineNo">272</span>   * list or string of size {@code size}. An element index may range from zero,<a name="line.272"></a>
<span class="sourceLineNo">273</span>   * inclusive, to {@code size}, exclusive.<a name="line.273"></a>
<span class="sourceLineNo">274</span>   *<a name="line.274"></a>
<span class="sourceLineNo">275</span>   * @param index a user-supplied index identifying an element of an array, list<a name="line.275"></a>
<span class="sourceLineNo">276</span>   *     or string<a name="line.276"></a>
<span class="sourceLineNo">277</span>   * @param size the size of that array, list or string<a name="line.277"></a>
<span class="sourceLineNo">278</span>   * @return the value of {@code index}<a name="line.278"></a>
<span class="sourceLineNo">279</span>   * @throws IndexOutOfBoundsException if {@code index} is negative or is not<a name="line.279"></a>
<span class="sourceLineNo">280</span>   *     less than {@code size}<a name="line.280"></a>
<span class="sourceLineNo">281</span>   * @throws IllegalArgumentException if {@code size} is negative<a name="line.281"></a>
<span class="sourceLineNo">282</span>   */<a name="line.282"></a>
<span class="sourceLineNo">283</span>  public static int checkElementIndex(int index, int size) {<a name="line.283"></a>
<span class="sourceLineNo">284</span>    return checkElementIndex(index, size, "index");<a name="line.284"></a>
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<span class="sourceLineNo">286</span><a name="line.286"></a>
<span class="sourceLineNo">287</span>  /**<a name="line.287"></a>
<span class="sourceLineNo">288</span>   * Ensures that {@code index} specifies a valid &lt;i&gt;element&lt;/i&gt; in an array,<a name="line.288"></a>
<span class="sourceLineNo">289</span>   * list or string of size {@code size}. An element index may range from zero,<a name="line.289"></a>
<span class="sourceLineNo">290</span>   * inclusive, to {@code size}, exclusive.<a name="line.290"></a>
<span class="sourceLineNo">291</span>   *<a name="line.291"></a>
<span class="sourceLineNo">292</span>   * @param index a user-supplied index identifying an element of an array, list<a name="line.292"></a>
<span class="sourceLineNo">293</span>   *     or string<a name="line.293"></a>
<span class="sourceLineNo">294</span>   * @param size the size of that array, list or string<a name="line.294"></a>
<span class="sourceLineNo">295</span>   * @param desc the text to use to describe this index in an error message<a name="line.295"></a>
<span class="sourceLineNo">296</span>   * @return the value of {@code index}<a name="line.296"></a>
<span class="sourceLineNo">297</span>   * @throws IndexOutOfBoundsException if {@code index} is negative or is not<a name="line.297"></a>
<span class="sourceLineNo">298</span>   *     less than {@code size}<a name="line.298"></a>
<span class="sourceLineNo">299</span>   * @throws IllegalArgumentException if {@code size} is negative<a name="line.299"></a>
<span class="sourceLineNo">300</span>   */<a name="line.300"></a>
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<span class="sourceLineNo">302</span>      int index, int size, @Nullable String desc) {<a name="line.302"></a>
<span class="sourceLineNo">303</span>    // Carefully optimized for execution by hotspot (explanatory comment above)<a name="line.303"></a>
<span class="sourceLineNo">304</span>    if (index &lt; 0 || index &gt;= size) {<a name="line.304"></a>
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<span class="sourceLineNo">313</span>    } else if (size &lt; 0) {<a name="line.313"></a>
<span class="sourceLineNo">314</span>      throw new IllegalArgumentException("negative size: " + size);<a name="line.314"></a>
<span class="sourceLineNo">315</span>    } else { // index &gt;= size<a name="line.315"></a>
<span class="sourceLineNo">316</span>      return format("%s (%s) must be less than size (%s)", desc, index, size);<a name="line.316"></a>
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<span class="sourceLineNo">318</span>  }<a name="line.318"></a>
<span class="sourceLineNo">319</span><a name="line.319"></a>
<span class="sourceLineNo">320</span>  /**<a name="line.320"></a>
<span class="sourceLineNo">321</span>   * Ensures that {@code index} specifies a valid &lt;i&gt;position&lt;/i&gt; in an array,<a name="line.321"></a>
<span class="sourceLineNo">322</span>   * list or string of size {@code size}. A position index may range from zero<a name="line.322"></a>
<span class="sourceLineNo">323</span>   * to {@code size}, inclusive.<a name="line.323"></a>
<span class="sourceLineNo">324</span>   *<a name="line.324"></a>
<span class="sourceLineNo">325</span>   * @param index a user-supplied index identifying a position in an array, list<a name="line.325"></a>
<span class="sourceLineNo">326</span>   *     or string<a name="line.326"></a>
<span class="sourceLineNo">327</span>   * @param size the size of that array, list or string<a name="line.327"></a>
<span class="sourceLineNo">328</span>   * @return the value of {@code index}<a name="line.328"></a>
<span class="sourceLineNo">329</span>   * @throws IndexOutOfBoundsException if {@code index} is negative or is<a name="line.329"></a>
<span class="sourceLineNo">330</span>   *     greater than {@code size}<a name="line.330"></a>
<span class="sourceLineNo">331</span>   * @throws IllegalArgumentException if {@code size} is negative<a name="line.331"></a>
<span class="sourceLineNo">332</span>   */<a name="line.332"></a>
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<span class="sourceLineNo">336</span><a name="line.336"></a>
<span class="sourceLineNo">337</span>  /**<a name="line.337"></a>
<span class="sourceLineNo">338</span>   * Ensures that {@code index} specifies a valid &lt;i&gt;position&lt;/i&gt; in an array,<a name="line.338"></a>
<span class="sourceLineNo">339</span>   * list or string of size {@code size}. A position index may range from zero<a name="line.339"></a>
<span class="sourceLineNo">340</span>   * to {@code size}, inclusive.<a name="line.340"></a>
<span class="sourceLineNo">341</span>   *<a name="line.341"></a>
<span class="sourceLineNo">342</span>   * @param index a user-supplied index identifying a position in an array, list<a name="line.342"></a>
<span class="sourceLineNo">343</span>   *     or string<a name="line.343"></a>
<span class="sourceLineNo">344</span>   * @param size the size of that array, list or string<a name="line.344"></a>
<span class="sourceLineNo">345</span>   * @param desc the text to use to describe this index in an error message<a name="line.345"></a>
<span class="sourceLineNo">346</span>   * @return the value of {@code index}<a name="line.346"></a>
<span class="sourceLineNo">347</span>   * @throws IndexOutOfBoundsException if {@code index} is negative or is<a name="line.347"></a>
<span class="sourceLineNo">348</span>   *     greater than {@code size}<a name="line.348"></a>
<span class="sourceLineNo">349</span>   * @throws IllegalArgumentException if {@code size} is negative<a name="line.349"></a>
<span class="sourceLineNo">350</span>   */<a name="line.350"></a>
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<span class="sourceLineNo">352</span>      int index, int size, @Nullable String desc) {<a name="line.352"></a>
<span class="sourceLineNo">353</span>    // Carefully optimized for execution by hotspot (explanatory comment above)<a name="line.353"></a>
<span class="sourceLineNo">354</span>    if (index &lt; 0 || index &gt; size) {<a name="line.354"></a>
<span class="sourceLineNo">355</span>      throw new IndexOutOfBoundsException(badPositionIndex(index, size, desc));<a name="line.355"></a>
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<span class="sourceLineNo">360</span>  private static String badPositionIndex(int index, int size, String desc) {<a name="line.360"></a>
<span class="sourceLineNo">361</span>    if (index &lt; 0) {<a name="line.361"></a>
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<span class="sourceLineNo">363</span>    } else if (size &lt; 0) {<a name="line.363"></a>
<span class="sourceLineNo">364</span>      throw new IllegalArgumentException("negative size: " + size);<a name="line.364"></a>
<span class="sourceLineNo">365</span>    } else { // index &gt; size<a name="line.365"></a>
<span class="sourceLineNo">366</span>      return format("%s (%s) must not be greater than size (%s)",<a name="line.366"></a>
<span class="sourceLineNo">367</span>                    desc, index, size);<a name="line.367"></a>
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<span class="sourceLineNo">370</span><a name="line.370"></a>
<span class="sourceLineNo">371</span>  /**<a name="line.371"></a>
<span class="sourceLineNo">372</span>   * Ensures that {@code start} and {@code end} specify a valid &lt;i&gt;positions&lt;/i&gt;<a name="line.372"></a>
<span class="sourceLineNo">373</span>   * in an array, list or string of size {@code size}, and are in order. A<a name="line.373"></a>
<span class="sourceLineNo">374</span>   * position index may range from zero to {@code size}, inclusive.<a name="line.374"></a>
<span class="sourceLineNo">375</span>   *<a name="line.375"></a>
<span class="sourceLineNo">376</span>   * @param start a user-supplied index identifying a starting position in an<a name="line.376"></a>
<span class="sourceLineNo">377</span>   *     array, list or string<a name="line.377"></a>
<span class="sourceLineNo">378</span>   * @param end a user-supplied index identifying a ending position in an array,<a name="line.378"></a>
<span class="sourceLineNo">379</span>   *     list or string<a name="line.379"></a>
<span class="sourceLineNo">380</span>   * @param size the size of that array, list or string<a name="line.380"></a>
<span class="sourceLineNo">381</span>   * @throws IndexOutOfBoundsException if either index is negative or is<a name="line.381"></a>
<span class="sourceLineNo">382</span>   *     greater than {@code size}, or if {@code end} is less than {@code start}<a name="line.382"></a>
<span class="sourceLineNo">383</span>   * @throws IllegalArgumentException if {@code size} is negative<a name="line.383"></a>
<span class="sourceLineNo">384</span>   */<a name="line.384"></a>
<span class="sourceLineNo">385</span>  public static void checkPositionIndexes(int start, int end, int size) {<a name="line.385"></a>
<span class="sourceLineNo">386</span>    // Carefully optimized for execution by hotspot (explanatory comment above)<a name="line.386"></a>
<span class="sourceLineNo">387</span>    if (start &lt; 0 || end &lt; start || end &gt; size) {<a name="line.387"></a>
<span class="sourceLineNo">388</span>      throw new IndexOutOfBoundsException(badPositionIndexes(start, end, size));<a name="line.388"></a>
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<span class="sourceLineNo">391</span><a name="line.391"></a>
<span class="sourceLineNo">392</span>  private static String badPositionIndexes(int start, int end, int size) {<a name="line.392"></a>
<span class="sourceLineNo">393</span>    if (start &lt; 0 || start &gt; size) {<a name="line.393"></a>
<span class="sourceLineNo">394</span>      return badPositionIndex(start, size, "start index");<a name="line.394"></a>
<span class="sourceLineNo">395</span>    }<a name="line.395"></a>
<span class="sourceLineNo">396</span>    if (end &lt; 0 || end &gt; size) {<a name="line.396"></a>
<span class="sourceLineNo">397</span>      return badPositionIndex(end, size, "end index");<a name="line.397"></a>
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<span class="sourceLineNo">399</span>    // end &lt; start<a name="line.399"></a>
<span class="sourceLineNo">400</span>    return format("end index (%s) must not be less than start index (%s)",<a name="line.400"></a>
<span class="sourceLineNo">401</span>                  end, start);<a name="line.401"></a>
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<span class="sourceLineNo">403</span><a name="line.403"></a>
<span class="sourceLineNo">404</span>  /**<a name="line.404"></a>
<span class="sourceLineNo">405</span>   * Substitutes each {@code %s} in {@code template} with an argument. These<a name="line.405"></a>
<span class="sourceLineNo">406</span>   * are matched by position - the first {@code %s} gets {@code args[0]}, etc.<a name="line.406"></a>
<span class="sourceLineNo">407</span>   * If there are more arguments than placeholders, the unmatched arguments will<a name="line.407"></a>
<span class="sourceLineNo">408</span>   * be appended to the end of the formatted message in square braces.<a name="line.408"></a>
<span class="sourceLineNo">409</span>   *<a name="line.409"></a>
<span class="sourceLineNo">410</span>   * @param template a non-null string containing 0 or more {@code %s}<a name="line.410"></a>
<span class="sourceLineNo">411</span>   *     placeholders.<a name="line.411"></a>
<span class="sourceLineNo">412</span>   * @param args the arguments to be substituted into the message<a name="line.412"></a>
<span class="sourceLineNo">413</span>   *     template. Arguments are converted to strings using<a name="line.413"></a>
<span class="sourceLineNo">414</span>   *     {@link String#valueOf(Object)}. Arguments can be null.<a name="line.414"></a>
<span class="sourceLineNo">415</span>   */<a name="line.415"></a>
<span class="sourceLineNo">416</span>  @VisibleForTesting static String format(String template,<a name="line.416"></a>
<span class="sourceLineNo">417</span>      @Nullable Object... args) {<a name="line.417"></a>
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<span class="sourceLineNo">419</span><a name="line.419"></a>
<span class="sourceLineNo">420</span>    // start substituting the arguments into the '%s' placeholders<a name="line.420"></a>
<span class="sourceLineNo">421</span>    StringBuilder builder = new StringBuilder(<a name="line.421"></a>
<span class="sourceLineNo">422</span>        template.length() + 16 * args.length);<a name="line.422"></a>
<span class="sourceLineNo">423</span>    int templateStart = 0;<a name="line.423"></a>
<span class="sourceLineNo">424</span>    int i = 0;<a name="line.424"></a>
<span class="sourceLineNo">425</span>    while (i &lt; args.length) {<a name="line.425"></a>
<span class="sourceLineNo">426</span>      int placeholderStart = template.indexOf("%s", templateStart);<a name="line.426"></a>
<span class="sourceLineNo">427</span>      if (placeholderStart == -1) {<a name="line.427"></a>
<span class="sourceLineNo">428</span>        break;<a name="line.428"></a>
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<span class="sourceLineNo">430</span>      builder.append(template.substring(templateStart, placeholderStart));<a name="line.430"></a>
<span class="sourceLineNo">431</span>      builder.append(args[i++]);<a name="line.431"></a>
<span class="sourceLineNo">432</span>      templateStart = placeholderStart + 2;<a name="line.432"></a>
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<span class="sourceLineNo">434</span>    builder.append(template.substring(templateStart));<a name="line.434"></a>
<span class="sourceLineNo">435</span><a name="line.435"></a>
<span class="sourceLineNo">436</span>    // if we run out of placeholders, append the extra args in square braces<a name="line.436"></a>
<span class="sourceLineNo">437</span>    if (i &lt; args.length) {<a name="line.437"></a>
<span class="sourceLineNo">438</span>      builder.append(" [");<a name="line.438"></a>
<span class="sourceLineNo">439</span>      builder.append(args[i++]);<a name="line.439"></a>
<span class="sourceLineNo">440</span>      while (i &lt; args.length) {<a name="line.440"></a>
<span class="sourceLineNo">441</span>        builder.append(", ");<a name="line.441"></a>
<span class="sourceLineNo">442</span>        builder.append(args[i++]);<a name="line.442"></a>
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<span class="sourceLineNo">444</span>      builder.append(']');<a name="line.444"></a>
<span class="sourceLineNo">445</span>    }<a name="line.445"></a>
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<span class="sourceLineNo">447</span>    return builder.toString();<a name="line.447"></a>
<span class="sourceLineNo">448</span>  }<a name="line.448"></a>
<span class="sourceLineNo">449</span>}<a name="line.449"></a>




























































</pre>
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